生物多样性丧失的生态效应被低估
文章来源:未知 文章作者:meng 发布时间:2010-12-01 02:10 字体: [ ]  进入论坛
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Children aren't the only youngsters who are picky(挑剔的) eaters: More than half of all species are believed to change their diets -- sometimes more than once -- between birth and adulthood1. And a new study by ecologists at Rice University and the University of California, Santa Barbara, finds this pattern has major implications for the survival of threatened species and the stability of natural ecosystems3. With thousands of species facing Earth's sixth major mass extinction4, there is little doubt that the planet's biodiversity is in rapid decline. But many questions remain about how natural ecosystems will respond to the lost diversity. The new study, published online this week in Ecology Letters, challenges one of the standard assumptions that ecologists have used for decades to analyze5 the effects of biodiversity loss on ecosystems. That assumption -- that all food resources used by a species are interchangeable(可互换的) among all members of the species -- fails to account for the fact that diets change as young animals develop into adults, said Rice ecologist Volker Rudolf, one of the study's co-authors. The findings by Rudolf and co-author Kevin Lafferty suggest that changing dietary needs within species have important implications for ecosystem2 health.

"If a species has three resources in an ecosystem, and we take away one, conventional wisdom suggests that that species should be fine," said Rudolf, assistant professor in ecology and evolutionary6 biology. "But if the missing resource is crucial for a particular developmental stage of the species, that just doesn't work. You can't take away all of the adults, for example, or all of the larvae7(幼虫) , and assume that the species will persist."

He said the new study was made possible by a wealth of information from recent datasets collected by Lafferty and colleagues at UC Santa Barbara. The datasets cover seven food webs --each representing the network of connections between dozens and, in some cases, hundreds of species in an ecosystem. Rudolf said Lafferty's food webs include data about specific resource requirements for particular developmental stages within species, in some instances for as many as 50 percent of the species in the ecosystem.

"With this data, we were able to estimate the percentage of resources that are actually shared among developmental stages," Rudolf said. "In addition, we were able to show how this affects the stability of natural ecosystems.

"We found that in most food webs, the individual stages of a species typically share less than 50 percent of their resources," he said. "And within certain subgroups, like metamorphic(变质的,变性的) species, that number is sometimes less than 10 percent."

The researchers used the information to formulate8 computer models that simulated how the loss of species affects natural ecosystems. One important implication of the finding is that natural ecosystems are much less stable than previously9 assumed, and many at-risk species may face an even greater likelihood of becoming extinct than ecologists previously thought.

"Our results suggest that the increasing loss of biodiversity -- due to changing climate, habitat destruction and other causes -- will likely have much more devastating10 effects on natural communities and result in a greater number of species extinctions than previously believed," Rudolf said.



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1 adulthood vKsyr     
n.成年,成人期
参考例句:
  • Some infantile actions survive into adulthood.某些婴儿期的行为一直保持到成年期。
  • Few people nowadays are able to maintain friendships into adulthood.如今很少有人能将友谊维持到成年。
2 ecosystem Wq4xz     
n.生态系统
参考例句:
  • This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
  • We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。
3 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
4 extinction sPwzP     
n.熄灭,消亡,消灭,灭绝,绝种
参考例句:
  • The plant is now in danger of extinction.这种植物现在有绝种的危险。
  • The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。
5 analyze RwUzm     
vt.分析,解析 (=analyse)
参考例句:
  • We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
  • The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。
6 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
7 larvae w2CxP     
n.幼虫
参考例句:
  • Larvae are parasitic on sheep.幼虫寄生在绵羊的身上。
  • The larvae prey upon small aphids.这种幼虫以小蚜虫为食。
8 formulate L66yt     
v.用公式表示;规划;设计;系统地阐述
参考例句:
  • He took care to formulate his reply very clearly.他字斟句酌,清楚地做了回答。
  • I was impressed by the way he could formulate his ideas.他陈述观点的方式让我印象深刻。
9 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
10 devastating muOzlG     
adj.毁灭性的,令人震惊的,强有力的
参考例句:
  • It is the most devastating storm in 20 years.这是20年来破坏性最大的风暴。
  • Affairs do have a devastating effect on marriages.婚外情确实会对婚姻造成毁灭性的影响。
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